1. Technical Field
The disclosure relates to the removal of solids from industrial, municipal, agricultural, or other wastewater or fluids.
2. Background
There is currently a severe shortage of usable water in many geographic locations. Moreover, the system for delivering, reclaiming or processing water for use is expensive and inefficient and achieved by a crumbling infrastructure. Current systems of industrial water filtration employ settling tanks or ponds that rely on large tracts of land and are only partially effective at particulate removal or dead end filtration which are very high cost and low volume.
It has been said that “water is the oil of the 21st century” because of huge demand and finite supply. Although it is estimated that greater than 75% of the earth's surface is covered by water, over 96% of water is ocean. Nearly 70% of freshwater is trapped in ice caps, glaciers and permanent snow. That leaves only a few percent as fresh water for human use (See, www.earthobservatory.nasa.gov.) Salt water, which represents the vast majority of water, requires expensive and energy intensive desalination processes before it is can be used for drinking.
The U.S. alone has more than 97,000 water treatment facilities. The projected annual growth rate for water treatment is 5%-8% over the next decade. Furthermore, the Environmental Protection Agency (EPA) has projected that this increase will come primarily from population growth and urban expansion. Because of increased demand, there is recognized a need to upgrade equipment and infrastructure used in the water treatment industry, particularly the wastewater treatment industry. Equipment installed under the Clean Water Act of 1972 is currently approaching the end of its projected lifecycle. In addition, the water treatment standards mandated by the EPA do, from time to time, become more stringent.
To make matters more complex, the issues pertaining to water as a resource and energy reserves are intertwined on many levels. An April 2005 Lawrence Berkeley National Laboratory Study estimated the electricity potential from methane produced by the anaerobic digestion of wastewater biosolids, from Industrial, Agriculture, and Municipal facilities. See E O. Lawrence Berkeley National Laboratory Study, April 2005, LBNL-57451. The results of the study demonstrated that, notwithstanding energy requirements to process water, the processing of water can itself be a source of energy
Traditionally, conventional waste water treatment facilities 10 are constructed to take in wastewater as influent and process it through a variety of screenings and treatments, as illustrated in FIG. 1, prior to the releasing the effluent to the ocean, bay, river or lake. Wastewater 12 that passes through the bar screen and the grit screen 14 is subjected to primary treatment in a large sedimentation lagoon or tank 20. The sedimentation tank 20 enables particle settling or sedimentation 22. The sedimentation tank has an influent which travels in at a very slow flow rate to an opposing end where it exits as effluent 24. During the process of traveling from the inlet (as influent) to the outlet (as effluent), particles settle out in a settling zone to form a sludge or sedimentation 22 at the bottom of the sedimentation tank 20. A variety of techniques can be employed to remove the particles from the sedimentation tank 20 that would be known to those skilled in the art.
The effluent 24 flows from the sedimentation tank 20 to a second sedimentation lagoon 30 where bubblers 32 aerate the influent and flocculants are added as part of a secondary treatment process. After secondary treatment the effluent 34 is often treated with a final disinfectant step by placing into a chlorination basin 40 prior to emitting the final effluent 42 into the ocean, bay, river or lake 50.
Conventional treatment technologies include, for example, a pumped diffusion flash mixer for chemical addition, flocculation basin, sedimentation basin and granular medium filter. The residuals from the wastewater treatment plant are returned to the source or stored in ponds. For example in arid locations, drying ponds are sometimes used. More often, mechanical processing is employed in conjunction with the residuals to reduce the volume of the residuals. Yet another treatment mechanism that can be used after primary treatment is provided by G.E. Water & Processing Technologies and includes ZeeWeed based membrane bioreactor (MBR). The ZeeWeed MBR is a basic production train that consists of a biological reactor, membrane basin, permeate pump, air blowers and automated control equipment. The production trains are simply expanded to meet capacity requirements as needed. Membrane bioreactor systems offer a significantly smaller footprint and simplified operation than the comparable conventional activated sludge systems shown in FIG. 1. However, the bioreactor systems are still quite large.
Currently there are several important issues facing the design of wastewater treatment facilities for which there has been an insufficient solution. First, most wastewater treatment facilities consume a significant amount of energy during operation. Second, wastewater treatment facilities typically require a substantial amount of land. Third, wastewater treatment facilities often emit an unpleasant odor which can make them undesirable to place strategically in an urban setting, notwithstanding the space requirements. Fourth, as much as 40% of the treated water is lost to evaporation during processing.
Industrial wastewater processes parallel the municipal systems outlined above but usually incorporate only one or two processes of those outlined above. For example, food processors need to recover and reuse fruit and vegetable pre-wash water but must satisfy strict EPA regulations to do so. Most food processors do not have an economical choice for recovering water for reuse and suffer higher costs to buy more water as well as local regulatory limitations on the amount of water that might be available from their local municipal water source. The effluent from these plants must also conform to EPA rules and the settling pond is a common solution. However, little or no water reclamation is possible.
Dead-end filter systems for large scale processing are large, consume significant amounts of energy and are expensive to build and maintain.
Systems previously developed include, for example, U.S. Pat. No. 3,950,249 to Eger et al. for Sanitary Waste Treatment Plant, U.S. Pat. No. 7,243,912 to Petit et al. for Aeration Diffuser Membrane Slitting Pattern, U.S. Pat. No. 7,309,427 to Kruse et al. for System for Treating Liquids. U.S. Pat. No. 7,314,564 to Kruse et al. for Method for Treating Liquids, U.S. Pat. No. 7,329,358 to Wilkins et al. for Water Treatment Process, and U.S. Pat. No. 7,563,351 to Wilkins et al. for Water Treatment System and Method; U.S. Patent Pubs. US 2002/0148779 A1 to Shieh et al. for Methods and Apparatus for Biological Treatment of Aqueous Waste, US 2003/0015469 A1 to Hedenland et al. for Modified Intermittent Cycle, Extended Aeration System (MICEAS), US 2005/0252855 A1 to Shieh et al. for Methods and Apparatus for Biological Treatment of Aqueous Waste, and US 2006/0254979 A1 to Koopmans et al. for Mixer and Process Controller for Use in Wastewater Treatment Processes.
What is needed, therefore, are systems, devices and methods for processing water which have a smaller footprint, reduce the amount of water lost to evaporation, provide for odor control, which have a reduced energy consumption and which are affordable and scaleable for non-municipal applications.